This invention relates to a method and apparatus for curing the lining of a pipe.
In this specification, reference to the lining of a pipe is intended to include many different types of pipe, and particularly underground pipes which may be pre-formed pipes subsequently installed underground, or pipes which are fabricated underground e.g. brick-lined sewers. Re-lining of existing pipes is a particularly convenient means of repairing existing pipes, conduits, pipelines and sewer walls.
It should be understood therefore that this invention has general application to the lining of pipes.
In certain applications, the lining of a pipe wall utilises a knitted glass fabric, optionally with granite or other filler material, plus a curable resin impregnated into the fabric. This type of lining material is particularly suitable for being taken around bends. The lining is then subsequently cured by use of a travelling curing apparatus. A typical known apparatus comprises a frame for introduction into the pipe, a curing lamp mounted on the frame, and a cord attached to the frame. The cord is passed along the pipe and is then used to pull the frame slowly through the pipe, and internally of the lining, thereby curing the lining as it travels. The curing lamp usually takes the form f an ultra-violet lamp, which is capable of curing the resin as the apparatus travels along the pipe.
However, heat is necessarily generated by the ultra-violet light, and in addition the curing action of the resin also generates heat, and these two factors can cause overheating of the lining, and with risk of combustion of the lining taking place.
In order to overcome this problem, pipelines are often filled with water before the curing apparatus is introduced The water acts as a coolant, but has the disadvantage of necessitating the use of expensive and potentially dangerous water proof ultra-violet lamps and associated electrical circuits.
The invention therefore seeks to provide method and apparatus for curing a lining of a pipe, having improved propelling means. Desirably, the improved propelling means also permits cooling of the internal wall of the lining during the curing process.
According to one aspect of the invention there is provided apparatus for curing the lining of a pipe and which comprises:
a travelling frame for introduction into the pipe;
a curing device mounted, or being capable of being mounted on the frame and operative to cure the inner wall of the lining during travel of the frame along the pipe; and
a fluid pressure driven propelling device connected to the frame and operative, upon application of fluid pressure to the pipe, to pull the frame along the pipe.
The apparatus therefore is propelled along the length of the lining by any suitable fluid pressure mediums which acts on the propelling device, and simultaneously the pressure medium also can act as a coolant preventing overheating and possible combustion of the lining.
Preferably, compressed air is utilised as the fluid pressure driving medium, since air is an insulator, and this enables a relatively inexpensive curing device e.g. an ultra-violet lamp, to be utilised for the curing operation, ant there would be no need for an expensive and potentially dangerous electrically insulated lamp, for use in the event of a non insulating fluid pressure medium being utilised.
In use of known curing devices, it is necessary to have access to both ends of the pipe, enabling the device to be inserted at one end and pulled through the pipe to the other end. By contrast, apparatus according to the invention may be used when only one end of the pipe can be accessed. In this case, the apparatus is propelled from the open end to the closed end, and then pulled back to the open end by a cord attached to the Frame. One preferred form of fluid pressure driven propelling device comprises an inflatable parachute or drogue. The diameter of the parachute, when inflated, mass be arranged to be larger than the diameter of the pipe along which it is travelling. This is advantageous in that, when the parachute is inflated, the fluid pressure driving medium e.g. air is not free to pass from the high pressure side of the parachute to the low pressure side of the parachute. Therefore, all the pressurised air introduced into the pipe can be used to propel the apparatus along the pipe. If necessary, large pressures can be built-up behind the parachute, if the apparatus is proving particularly difficult to move.
However, in other circumstances, it may be desirable for the diameter of the inflated parachute to be less than the diameter of the pipe. This has the advantage that a portion of the fluid pressure medium e.g. compressed air, introduced into the pipe can be used to inflate that parachute and propel the frame, but still leaving a further portion of the medium to travel over the apparatus and the parachute, and also the curing device as well as the lining, and thereby dissipating any heat generated, and cooling the lining so as to minimise the risk of combustion.
In a further preferred arrangement, regardless of whether the parachute is oversized or undersized, when inflated, relative to the pipe, the parachute may be arranged to be semi-permeable relative to the fluid pressure driving medium. This has the advantage that a predetermined portion of the medium introduced into the pipe can pass through the parachute, thereby cooling the pipe lining, and With the remainder of the medium being used to inflate the parachute and propel the frame along the pipe. The ratio of the driving and Cooling portions of the medium introduced In to the pipe can be determined in advance, and will remain constant even if the diameter of the pipe changes.
Desirably, the travelling frame is adjustable in width, which enables the frame to be used in pipe linings of different diameter. The diameter of the frame may be adjusted such that the curing device e.g. an ultra-violet lamp, is always in the center of the pipe and does not lie at the bottom of large pipelines.
The frame may have wheels attached thereto to facilitate the motion of the frame along the pipe.
The frame may also carry a power source for powering the curing device.
The frame may also include a propeller to assist in inflation of the parachute. With such a propeller, there is no need for an external device connected to the end of the pipe for introducing the fluid pressure medium. Such a propeller may be useful in particularly long pipes where the volume of pressurised fluid to be introduced might be excessive, id the absence of the propeller.
An alternative embodiment of fluid pressure driven propelling device which may be connected to the frame may comprise a so-called pipeline xe2x80x9cpigxe2x80x9d, of the type used in scraping and cleaning the internal walls of pipelines. Many designs of xe2x80x9cpigxe2x80x9d have been proposed, and particularly for use in cleaning, he walls of pipelines conveying hydrocarbons, and which include designs of pig which are particularly suitable for negotiating pipeline bends, and which may be particularly suitable for use in the apparatus of the invention.
According to a further aspect of the invention, there is provided a method of curing the lining of a pipe utilising an apparatus as defined above, and/or utilising any one or more of the preferred options referred to above.